Insert holder and method of holding

ABSTRACT

A toolholder for releasably holding an indexable cutting insert is described. The insert is locked onto an insert receiving pocket on the toolholder by a locking pin whose head clamps against an upwardly facing wall in a tapered central aperture through the insert. The pin is threadedly engaged to the toolholder and is configured so as to allow itself to tilt outwardly, after the insert is unclamped, allowing the insert to be removed from the pin and the insert pocket.

BACKGROUND OF THE INVENTION

This invention pertains to toolholders for holding cutting inserts usedin the metalworking field. It especially pertains to toolholdersutilizing tiltable locking pins and methods of locking indexable cuttinginserts onto toolholders.

Previous insert clamping mechanisms, as exemplified by U.S. Pat. Nos.3,341,920 and 3,341,921, utilize a conical bore whose axis is offsetfrom the threaded section of the locking pin receiving hole to tilt thelocking pin into abutment with the cutting insert. These designs aredifficult to machine since the location of the conical bore must bemaintained within relatively tight tolerances if it is to achieve thedesired tilting of the locking pin.

Other toolholder designs utilizing tilting or laterally moving lockingpins are described in U.S. Pat. Nos. 3,533,150; 3,654,682; 3,662,444;3,623,201; and 3,747,179.

BRIEF SUMMARY OF THE INVENTION

According to the present invention, a toolholder for use in holding acutting insert is provided. This toolholder has a body portion with aninsert receiving pocket on it. The pocket has a planar bottom wall, atleast one side wall extending upwardly from the bottom wall, and a pinreceiving hole formed downwardly through, and substantially normal to,the bottom wall. The pin receiving hole has a threaded section and asmooth bore section.

In accordance with the present invention, a locking pin is alsoprovided. This locking pin has a head for clamping against a cuttinginsert, a threaded portion for engagement with the threaded section inthe pin receiving hole, and an increased cross section bearing means, orincreased diameter section, for snugly and slidingly engaging the smoothbore of the pin receiving hole.

The pin clamping head comprises a first and second diameter with thefirst diameter being smaller than the second diameter. A downwardlyfacing locking shoulder is formed between the first and seconddiameters. This clamping head is designed for use with a cutting inserthaving a tapered aperture with a wall of said aperture forming a lockingface facing upwardly. According to one embodiment of the presentinvention, the threaded portion of the pin has reduced pitch diameterthreads so as to allow the pin to tilt while still being threadedlyengaged in the pin receiving hole. In this embodiment, the increasedcross section portion of the pin is located between the clamping headand threaded portion. When the locking pin according to this embodimentis rotated to a first position, the threaded portion of the pin and thehole are at least partially engaged with one another and the pin istiltable so as to allow the locking pin clamping head to be insertedinto the insert aperture.

When the locking pin is rotated to a second position, the increaseddiameter section of the pin slidingly engages the smooth bore section ofthe pin receiving hole, thereby holding the pin substantially laterallyfixed or nontiltable. In this position, the cutting insert is looselyheld captive on the insert pocket by the clamping head. When the pin isrotated from this second position to a third position, the pin is moveddownward along the axis of the pin receiving hole, which causes thelocking shoulder of the upper portion of the pin to abut the upwardlyfacing wall or locking face of the insert aperture and firmly clamp theinsert into the insert receiving pocket.

In another embodiment of the present invention, the threaded portion islocated between the clamping head and the increased cross sectionbearing means. In this embodiment, the increased cross section bearingmeans has an outer lateral surface which tapers inwardly as it extendsoutwardly from the pin.

This embodiment allows the pin to tilt in the pin receiving hole toreceive a cutting insert when the pin is not threadedly engaged with thethreaded section of the hole. When the pin is threadedly engaged withthe pin receiving hole, the pin is no longer tiltable and is operable toclamp the cutting insert into the insert pocket in the manner describedabove in the first embodiment.

Therefore, in accordance with the features described above, it is anobject of the present invention to provide a toolholding arrangementwhich may be relatively cheaply and easily manufactured.

It is also an object of the present invention to provide a toolholdingarrangement in which a cutting insert may be replaced without removingthe locking pin from the toolholder body.

It is also an object of the present invention to provide an insertclamping arrangement and method in which an insert is clamped bothdownwardly and laterally in the insert pocket.

BRIEF DESCRIPTION OF THE DRAWINGS

The exact nature of the present invention will become more clearlyapparent upon reference to the following detailed specification taken inconnection with the accompanying drawings in which:

FIG. 1 shows a toolholder, with a cutting insert locked thereon by alock pin according to the present invention.

FIG. 2 is a vertical longitudinal section along line II--II of FIG. 1showing a negative rake insert being loaded onto the toolholder.

FIG. 3 is a view of the same embodiment shown in FIG. 2 except that thepin has been rotated to a second position in which it is heldnontiltable, and it, in turn, holds the insert loosely captive on theinsert pocket.

FIG. 4 is a view of the same embodiment shown in FIG. 3 except that thepin has been rotated from the second to a third position in which it isnow firmly clamping the insert onto the insert pocket.

FIG. 5 is a preferred embodiment of the locking pin and toolholder bodyaccording to the present invention.

FIG. 6 is a longitudinal diametric cross section of the reduced pitchdiameter threads shown in FIGS. 2 through 5.

FIGS. 7 and 8 are alternate embodiments of the reduced pitch diameterthreads shown in FIG. 6.

FIG. 9 shows a fragmentary view of an alternate embodiment of atoolholder and locking pin according to the present invention.

FIG. 10 shows another alternate embodiment of a toolholder and lockingpin according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the drawings somewhat more in detail, as can be seen inFIG. 1, the present invention consists of a toolholder 1 for holding acutting insert 3. The cutting insert may be a negative rake insert, asshown in FIG. 1, a positive rake cutting insert, or any of the otherinsert styles known in the art. The toolholder 1 comprises a toolholderbody 5 and a locking pin 7. The locking pin 7 has a head portion 23which fits into a tapered aperture 6 in the cutting insert 3 and clampsagainst a side wall or locking face of that tapered aperture so as tohold the cutting insert 3 on an insert seat on the toolholder body 5.

Referring now to FIGS. 2, 3 and 4, the details of the present inventionare more clearly shown. These figures consist of sections taken alongline II--II of FIG. 1 and show how the present invention operates toclamp the cutting insert 3 onto the tooldholder body 5.

In FIG. 2, a toolholder body 5 is shown having an insert receivingpocket 11. The insert receiving pocket 11 has a side wall 13 rising upfrom a bottom wall 15. Formed downwardly through, and substantiallyperpendicularly to, the bottom wall 15 is a pin receiving hole 17.Preferably, the pin receiving hole 17 is aligned normally to the bottomwall 15. This preferred design simplifies manufacture of the toolholderbody 5 since both the insert receiving seat 11 and pin receiving hole 17can be machined in one machining set up rather than the two set ups thatmay be required when the pin receiving hole is not normal to the bottomwall of the insert receiving pocket. This pin receiving hole 17 has asmooth bore section 21 and a threaded section 19.

At least partially engaged in the threaded section 19 of the pinreceiving hole 17 is a locking pin 7. The locking pin 7 has an upperportion 23 which has a first 35 and a second 36 diameter with the firstdiameter being smaller than the second diameter. Formed between thefirst and second diameter is a downwardly facing locking shoulder 25which will be used to abut against a tapered aperture 6 in the insert 3.The second diameter is sized so as to fit within a reduced diameterportion 4 of the insert aperture.

At the other end of the locking pin 7 is a threaded portion 27. Thisthreaded portion has reduced pitch diameter threads on it. Locatedbetween the upper portion 23 and the threaded portion 27 is an increaseddiameter section 29. As can be seen in this figure, a flange 33 may belocated near the top of the increased diameter section 29 when a shimmember 31 is used for mounting the insert 3.

In the position of the pin 7 shown in FIG. 2, it can be seen that thereduced pitch diameter threads 27 are at least partially engaged in thethreaded section 19 of the pin receiving hole 17. This allows thelocking pin 7 to be tilted outwardly from the side wall 13 of the insertreceiving pocket 11 while still being retained in the pin receiving hole17. In this position, a cutting insert 3 having a tapered aperture 6with an upwardly facing wall or locking face 9 may be slid over theupper portion of the locking pin 7.

After the cutting insert 3 has been mounted upon the lock pin 7, thelocking pin 7 is rotated so that it draws itself further downwardly intothe pin receiving hole 17 as shown in FIG. 3. In FIG. 3, it can be seennow that the locking pin 7 has been drawn into the pin receiving hole 17to such an extent that the increased diameter portion 29 of the pin 7 isin sliding and snug engagement with the smooth bore section 21 of thepin receiving hole 17. The locking pin 7 is thereby held substantiallylaterally fixed or nontiltable.

When the pin 7 is so engaged, the longitudinal axis, or a center line ofthe pin, is held parallel to the axis I--I of the cutting insertaperture 6. However, the axis P--P of the locking pin 7 and the axisI--I of the cutting insert 3 are not colinear, the axis P--P of thelocking pin 7 being closer to the side wall 13 than the axis I--I of thecutting insert. In this second position, the downwardly facing lockingshoulder 25 of the upper portion of the pin 23 acts to loosely holdcaptive the cutting insert 3.

As the locking pin 7 is rotated further inwardly into the pin receivinghole 17, the downwardly facing locking shoulder 25 on the upper portionof the locking pin 7 now comes into contact with the upwardly facingwall or locking face 9 in the tapered aperture 6 of the cutting insert3.

When this occurs, the cutting insert is driven downwardly against eitherthe shim member 31 as shown in FIG. 4 or, where there is no shim used,against the bottom wall 15 of the insert receiving pocket 11. At thesame time that this is occurring, the insert is also being drivenlaterally against the side wall 13 of the insert receiving pocket 11.

It will be noted in viewing FIGS. 3 and 4 that the locking pin 7maintains its parallel relationship to the axis of the cutting insertand the axis of the pin receiving hole 17 during the clamping of theinsert 3 into the insert receiving pocket 11.

As shown in the figures, the locking pin 7 may have hex shaped openings8, or equivalents, at both ends of the pin 7 for engagement with asuitable rotation causing means.

FIG. 5 shows a preferred embodiment of the toolholder body and lockingpin. Locking pin 52 is shown having an increased diameter section whichis composed of two steps 54 and 60. Step 54 fits slidingly and snuglyinto a smooth bore 56 in the pin receiving hole 55 and step 60 fitssnugly and slidingly into a smooth bore 58 in the pin receiving hole 55.Step 60 has a smaller diameter than step 54 and is located between step54 and the threaded portion on the end of the locking pin. The purposeof forming the increased diameter section, as shown in FIG. 5, is toimprove the load bearing characteristics of the pin when the pin isclamped against the cutting insert. Locking pin 52, when clamped againsan insert, will bear the loads produced by the clamping in two areasdiametrically opposite to where the pin clamps against the insert; onearea on each of steps 54 and 60, rather than the one bearing areaproduced in the locking pin 7 increased diameter section 29.

FIG. 6 shows a longitudinal diametric cross portion of the threadedsection of the locking pin shown in FIGS. 2 through 5. It can be seenthat the threaded portion is made up of individual thread members havingpeaks 72. The peaks have been turned down on a lathe such that they forman imaginary envelope that appears to be bi-convex as shown in FIG. 6.

This shaping of the threads allows the locking pin 7 to easily tilt inthe threaded section 19 of the pin receiving hole 17 when the lockingpin 7 is positioned as shown in FIG. 2, while also allowing each threadto be engaged against the threads in threaded section 19, therebydistributing the vertical clamping load produced on the threads when theinsert is clamped as shown in FIG. 4.

Alternatively, instead of having the bi-convex shape shown in FIG. 6,the reduced pitch diameter threads can have the shapes shown in FIGS. 7and 8.

In FIG. 7, the individual thread members have had their peaks 82machined on a lathe such that the peaks 82 form a trapezoidal envelopewith the larger base on the upward side.

In FIG. 8, the reduced pitch diameter threads have had their ends 92machined on a lathe such that their ends form a trapezoidal envelopewith the larger base facing downward.

Shown in FIG. 9 is another alternative embodiment according to thepresent invention in which the threaded section 150 of a pin receivinghole has an increased pitch diameter threaded section 152. Thisembodiment would allow the use of a locking pin 154 having a standarduniformly threaded portion 156 in the present invention. When threadedportion 156 is engaged with the increased pitch diameter threadedsection 152, the pin 154 would be tiltable.

FIG. 10 shows an alternative embodiment to the toolholders and lockingpins shown in the previous figures. In FIG. 10, there is shown atoolholder 100 having a toolholder body 108 with an insert receivingpocket having a side wall 110 rising from a bottom wall 112. The bottomwall 112 has an insert receiving hole 114 formed downwardly andsubstantially perpendicular to it. This insert receiving hole 114 has athreaded section 116 and a smooth bore section 118.

Located in this pin receiving hole 114 is a locking pin 120. The lockingpin has an upper portion 122 with a downwardly facing shoulder 124. Atthe lower end of the locking pin 120 is an increased diameter section126. When viewed in profile, increased diameter section 126 has an outerperipheral surface 128 that tapers inwardly as it extends outwardly.Located between the upper portion 122 and the increased diameter section126 is a threaded portion 130.

As shown in this figure, the locking pin 120 clamps downwardly against atapered upwardly facing wall or locking face 106 in an insert aperture104 so as to clamp the insert 102 against the side wall 110 and thebottom wall 112 of the insert receiving pocket. This locking pin 120 canbe formed in a shorter length than the locking pin shown in FIGS. 2through 8, and is, therefore, ideally suited for toolholder bodies 108which are required to have a shallow depth. For example, toolholderbodies 108 having a short depth may be required on the periphery of aboring head 150.

The toolholder 100 operates as follows: When the threaded portion 130 ofthe locking pin 120 is out of engagement with the threaded section 116of the pin receiving hole 114, the pin 120 is able to tilt outwardlysince the increased diameter section 126 has a tapered peripheralsurface 128. At this point, the upwardly facing shoulder 129 of theincreased diameter section 126 may abut a downwardly facing shoulder 144in the pin receiving hole 114. It may also abut an abutment surface orpin 140 which protrudes into the smooth bore section 118 of the pinreceiving hole 114. Abutment pin 140 is optional and, when used inconjunction with spring 148 in recess 146, serves to automatically tiltthe pin 120 outwardly away from wall 110.

When the locking pin 120 is tilted outwardly, the cutting insert 102 maybe slid over the upper portion 122 of the locking pin 120. The lockingpin is then rotated so as to threadedly engage the threaded section 116of the pin receiving hole 114 and thereby becomes aligned parallel tothe axis of the pin receiving hole 114 and is no longer tiltable.

In this position, it holds the insert 102 captive in the insertreceiving pocket. Further rotation of the locking pin 120 downward intothe pin receiving hole 114 will bring the downwardly facing lockingshoulder 124 into abutment with the upwardly facing shoulder 126 wall orlocking face 106 on the cutting insert 102 and thereby drive the cuttinginsert into abutment with the side wall 110 and bottom wall 112 of theinsert receiving pocket thereby firmly securing it to the toolholderbody 108.

Modifications may be made within the scope of the appended claims.

What is claimed is:
 1. A toolholder for use in holding a cutting inserthaving a tapered aperture wherein a wall of said aperture forms alocking face, and wherein said toolholder comprises: a toolholder bodyand a cooperating locking pin means;said toolholder body comprising aninsert receiving pocket having a planar bottom wall and a side wallsubstantially normal to said bottom wall; and a pin receiving holeformed through, and substantially normal to, said bottom wall, said pinreceiving hole having a threaded section and a cylindrical smooth boresection; said locking pin means comprising a diametrical elongate body;a clamping head having a locking shoulder; a reduced pitch diameterthreaded portion; and a cylindrical increased diameter section locatedbetween said threaded portion and said locking shoulder; said lockingpin means rotatably mounted in said pin receiving hole with saidclamping head extending into said insert receiving pocket, with saidcylindrical increased diameter section snugly and slidingly engagingsaid smooth bore section and with the respective threaded portion andsection of said locking pin means and said pin receiving hole threadedlyengaged so that said rotation of said locking pin means advances orretracts said locking pin means in said pin receiving hole; said lockingpin means, when rotated to a first position and while at least partiallythreadedly engaged in said pin receiving hole, is freely tiltable so asto allow said clamping head to be inserted into said insert aperture;said locking pin means, when rotated to a second position, is heldsubstantially laterally fixed by the snug and sliding engagement of saidincreased diameter section with said smooth bore section, and whereinsaid locking pin means when in said second position loosely holds saidinsert captive in the toolholder pocket; and said locking pin means whenrotated from said second to a third position, causes said lockingshoulder of said clamping head to abut said locking face of said insertaperture and clamp said insert against said bottom and side wall of saidinsert receiving pocket.
 2. A toolholder according to claim 1 whereinsaid reduced pitch diameter threaded portion comprises, when viewed inlongitudinal diametric cross section, individual thread members havingends defining a biconvex envelope.
 3. A toolholder according to claim 1wherein said reduced pitch diameter threaded portion comprises, whenviewed in longitudinal diametric cross section, individual threadmembers having ends defining a trapezoidal envelope.
 4. A toolholder foruse in holding a cutting insert having a tapered aperture wherein a wallof said aperture forms a locking face, and wherein said toolholdercomprises: a toolholder body and a cooperating locking pin means;saidtoolholder body comprising an insert receiving pocket having a planarbottom wall and a side wall substantially normal to said bottom wall;and a pin receiving hole formed through, and substantially normal to,said bottom wall, said pin receiving hole having an increased pitchdiameter threaded section and a cylindrical smooth bore section; saidlocking pin means comprising a diametrical elongate body; a clampinghead having a locking shoulder; a threaded portion; and a cylindricalincreased diameter section located between said threaded portion andsaid locking shoulder; said locking pin means rotatably mounted in saidpin receiving hole with said clamping head extending into said insertreceiving pocket, with said cylindrical increased diameter sectionsnugly and slidingly engaging said smooth bore section and with therespective threaded portion and section of said locking pin means andsaid pin receiving hole threadedly engaged so that said rotation of saidlocking pin means advances or retracts said locking pin means in saidpin receiving hole; said locking pin means, when rotated to a firstposition and while at least partially threadedly engaged in said pinreceiving hole, is freely tiltable so as to allow said clamping head tobe inserted into said insert aperture; said locking pin means, whenrotated to a second position, is held substantially laterally fixed bythe snug and sliding engagement of said increased diameter section withsaid smooth bore section, and wherein said locking pin means when insaid second position loosely holds said insert captive in the toolholderpocket; and said locking pin means when rotated from said second to athird position, causes said locking shoulder of said clamping head toabut said locking face of said insert aperture and clamp said insertagainst said bottom and side wall of said insert receiving pocket.
 5. Atoolholder for use in holding a cutting insert having a tapered aperturewherein a wall of said aperture forms a locking face, and wherein saidtoolholder comprises: a toolholder body and a cooperating locking pinmeans;said toolholder body comprising an insert receiving pocket havinga planar bottom wall and a side wall substantially normal to said bottomwall; and a pin receiving hole formed through, and substantially normalto, said bottom wall, said pin receiving hole having a threaded sectionand a cylindrical smooth bore section; said locking pin means comprisinga diametrical elongate body; a clamping head having a locking shoulder;a threaded portion; and a cylindrical increased diameter section locatedbetween said threaded portion and said locking shoulder; said lockingpin means rotatably mounted in said pin receiving hole with saidclamping head extending into said insert receiving pocket, with saidcylindrical increased diameter section snugly and slidingly engagingsaid smooth bore section and with the respective threaded portion andsection of said locking pin means and said pin receiving hole threadedlyengaged so that said rotation of said locking pin means advances orretracts said locking pin means in said pin receiving hole; said lockingpin means, when rotated to a first position and while at least partiallythreadedly engaged in said pin receiving hole, is freely tiltable so asto allow said clamping head to be inserted into said insert aperture;said locking pin means, when rotated to a second position, is heldsubstantially laterally fixed by the snug and sliding engagement of saidincreased diameter section with said smooth bore section, and whereinsaid locking pin means when in said second position loosely holds saidinsert captive in the toolholder pocket; and said locking pin means whenrotated from said second to a third position, causes said lockingshoulder of said clamping head to abut said locking face of said insertaperture and clamp said insert against said bottom and side wall of saidinsert receiving pocket.
 6. A toolholder according to claims 5, 2, 3 or4 wherein the axis of said pin receiving hole is normal to said bottomwall.
 7. A toolholder according to claim 6 wherein said locking pinmeans further comprises a flanged section located in said receivingpocket; and wherein toolholder further comprises a shim member which isheld captive between said flanged section and said bottom wall.
 8. Acutting tool comprising: a cutting insert having a tapered centralaperture wherein a wall of said aperture forms a locking face, atoolholder body and a cooperating locking pin means;said toolholder bodycomprising an insert receiving pocket having a planar bottom wall and aside wall substantially normal to said bottom wall; and a pin receivinghole formed through, and substantially normal to, said bottom wall, saidpin receiving hole having a threaded section and a cylindrical smoothbore section; said locking pin means comprising a diametrical elongatebody; a clamping head having a locking shoulder; a threaded portion; anda cylindrical increased diameter section located between said threadedportion and said locking shoulder; said locking pin means rotatablymounted in said pin receiving hole with said clamping head extendinginto said insert receiving pocket, with said cylindrical increaseddiameter section snugly and slidingly engaging said smooth bore sectionand with the respective threaded portion and section of said locking pinmeans and said pin receiving hole threadedly engaged so that saidrotation of said locking pin means advances or retracts said locking pinmeans in said pin receiving hole; said locking pin means, when rotatedto a first position and while at least partially threadedly engaged insaid pin receiving hole, is freely tiltable so as to allow said clampinghead to be inserted into said insert aperture; said locking pin means,when rotated to a second position, is held substantially laterally fixedby the snug and sliding engagement of said increased diameter sectionwith said smooth bore section, and wherein said locking pin means whenin said second position loosely holds said insert captive in thetoolholder pocket; and said locking pin means when rotated from saidsecond to a third position, causes said locking shoulder of saidclamping head to abut said locking face of said insert aperture andclamp said insert against said bottom and side wall of said insertreceiving pocket.
 9. The toolholder of claims 5 or 8 further comprisinga second cylindrical smooth bore section smaller in diameter and closerto said threaded portion than said cylindrical smooth bore section, saidsmooth bore sections combining to form a stepped cylindrical boresection; a second cylindrical increased diameter section smaller indiameter and closer to said lower threaded portion than said cylindricalincreased diameter section, said increased diameter sections combiningto form a stepped cylindrical increased diameter section adapted forsnugly and slidingly engaging said stepped cylindrical bore section. 10.A cutting tool comprising: a cutting insert having a tapered centralaperture wherein a wall of said aperture forms a locking face, atoolholder body and a cooperating locking pin means;said toolholder bodycomprising an insert receiving pocket having a planar bottom wall and aside wall substantially normal to said bottom wall; and a pin receivinghole formed through, and substantially normal to, said bottom wall, saidpin receiving hole having a threaded section and a cylindrical smoothbore section; said locking pin means comprising a diametrical elongatebody; a clamping body head having a locking shoulder; a reduced pitchdiameter threaded portion; and a cylindrical increased diameter sectionlocated between said threaded portion and said locking shoulder; saidlocking pin means rotatably mounted in said pin receiving hole with saidclamping head extending into said insert receiving pocket, with saidcylindrical increased diameter section snugly and slidingly engagingsaid smooth bore section and with the respective threaded portion andsection of said locking pin means and said pin receiving hole threadedlyengaged so that said rotation of said locking pin means advances orretracts said locking pin means in said pin receiving hole; said lockingpin means, when rotated to a first position and while at least partiallythreadedly engaged in said pin receiving hole, is freely tiltable so asto allow said clamping head to be inserted into said insert aperture;said locking pin means, when rotated to a second position, is heldsubstantially laterally fixed by the snug and sliding engagement of saidincreased diameter section with said smooth bore section, and whereinsaid locking pin means when in said second position loosely holds saidinsert captive in the toolholder pocket; and said locking pin means whenrotated from said second to a third position, causes said lockingshoulder of said clamping head to abut said locking face of said insertaperture and clamp said insert against said bottom and side wall of saidinsert receiving pocket.
 11. A cutting tool according to claim 10wherein said reduced pitch diameter threaded portion comprises, whenviewed in longitudinal diametric cross section, individual threadmembers having ends defining a biconvex envelope.
 12. A cutting toolaccording to claim 10 wherein said reduced pitch diameter threadedportion comprises, when viewed in longitudinal diametric cross section,individual thread members having ends defining a trapezoidal envelope.13. A cutting tool comprising: a cutting insert having a tapered centralaperture wherein a wall of said aperture forms a locking face, atoolholder body and a cooperating locking pin means;said toolholder bodycomprising an insert receiving pocket having a planar bottom wall and aside wall substantially normal to said bottom wall; and a pin receivinghole formed through, and substantially normal to, said bottom wall, saidpin receiving hole having an increased pitch diameter threaded sectionand a cylindrical smooth bore section; said locking pin means comprisinga diametrical elongate body; a clamping head having a locking shoulder;a threaded portion; and a cylindrical increased diameter section locatedbetween said threaded portion and said locking shoulder; said lockingpin means rotatably mounted in said pin receiving hole with saidclamping head extending into said insert receiving pocket, with saidcylindrical increased diameter section snugly and slidingly engagingsaid smooth bore section and with the respective threaded portion andsection of said locking pin means and said pin receiving hole threadedlyengaged so that said rotation of said locking pin means advances orretracts said locking pin means in said pin receiving hole; said lockingpin means, when rotated to a first position and while at least partiallythreadedly engaged in said pin receiving hole, is freely tiltable so asto allow said clamping head to be inserted into said insert aperture;said locking pin means, when rotated to a second position, is heldsubstantially laterally fixed by the snug and sliding engagement of saidincreased diameter section with said smooth bore section, and whereinsaid locking pin means when in said second position loosely holds saidinsert captive in the toolholder pocket; and said locking pin means whenrotated from said second to a third position, causes said lockingshoulder of said clamping head to abut said locking face of said insertaperture and clamp said insert against said bottom and side wall of saidinsert receiving pocket.
 14. A cutting tool according to claims 8, 10,12 or 13 wherein the axis of said pin receiving hole is normal to saidbottom wall.
 15. A cutting tool according to claim 14 wherein saidlocking pin means further comprises a flanged section located in saidinsert receiving pocket; and wherein toolholder further comprises a shimmember which is held captive between said flanged section and saidbottom wall.
 16. A method of clamping a cutting insert having anaperture onto a toolholder, wherein the toolholder comprises atoolholder body and a cooperating locking pin means,said toolholder bodycomprising an insert receiving pocket having a planar bottom wall and aside wall substantially normal to said bottom wall; and a pin receivinghole formed through, and substantially normal to, said bottom wall, saidpin receiving hole having a threaded section and a cylindrical smoothbore section; said locking pin means comprising a diametrical elongatebody; a clamping head having a locking shoulder; a threaded portion; anda cylindrical increased diameter section located between said threadedportion and said locking shoulder, said increased diameter sectionadapted for snugly and slidingly engaging said smooth bore section; saidmethod comprising the steps of: threadedly engaging the threaded portionof the locking pin means in the threaded section of the pin receivinghole such that the clamping head extends into the insert receivingpocket; tilting the locking pin means away from the side wall andslidingly engaging the clamping head into the insert aperture while saidlocking pin means is at least partially threadedly engaged in said pinreceiving hole; aligning the locking pin means with the pin receivinghole; rotating the locking pin means into further threaded engagementwith the pin receiving hole to obtain snug and sliding engagementbetween the increased diameter section of the pin and the smooth bore ofthe hole, and thereby hold the pin substantially laterally fixed whileholding the insert loosely captive between the pin and the insertpocket; rotating the pin locking means further into the hole so as toclamp the insert into the pocket.
 17. A locking pin for securing acutting insert onto a toolholder body, wherein said locking pincomprises: an elongate diametrical body having a clamping head near oneend of said diametrical body; a threaded portion near the other end ofsaid diametrical body; a stepped increased diameter section locatedbetween said clamping head and said threaded portion, wherein saidstepped increased diameter comprises a first increased diameter portionand a second increased diameter portion, with said second increaseddiameter portion being smaller in diameter and closer to said threadedportion than said first increased diameter portion; and a flangedsection located between said stepped increased diameter section and saidclamping head.
 18. A locking pin according to claim 17 wherein saidthreaded portion comprises reduced pitch diameter threads.